Alkaline nickel plating solution



ALKALINE NlCKEL PLATING SOLUTION Paul W. Moy, Gates Mills, and Arthur H; 'DujRose Euclid, Ohio, assignors to The Harshaw 'Ch'emic'alCompany, Cleveland, Ohio, a corporation of'Ohio N Drawing. Application May 20, .1954, Serial -N0. 431,274

Claims. ((1204-49) -'Il1is-invention relates to electrodeposition of nickeland more specifically to alkaline nickel plating solutions and I:

processes of eleotrodeposition utilizing such solutions.

Several alkaline nickel plating solutions have beeii devised in the past but, so faras We are aware, they-have left much to be desired either in the quality of'thedeposit or in the behavior of the solution.

We have now discovered that by the inclusion in the consistently excellent deposits on zinc base die castings and other bodies composed or largely composed of Zinc and that such solutions exhibit very much improved stability. The complexing agents referred were the polyalkanoic acid derivatives of polyalkylene amines.

2,773,818 Patented Dec. 11, 1956 :(4).}-Disodium salt of ethylene diamine tetra acetic acid.

'(5) Trisodium-salt of-ethylene diamine tetra acetic acid.

(6) vTetrasodium-salt of ethylene diamine tetra acetic acid.

(7) Monosodium salt of diethylene triamine penta acetic acid.

(8) Disodium salt of diet'hyl'en'e triamine penta acetic acid.

(9) Trisodium saltof diethylene triamine-penta. acetic acid.

(10) Trisodium salt of t iethylene tetramine hexa acetic acid.

(11) Propylenediamine-tetra acetic acid.

g 12) T-risodium salt :of propylene diamine tetra acetic act j T so um s lt rmpyl e. d a ine, tet a P pionicacid. v

(l4) Trisodium salt ofdip'ropylene'triamine penta'pro pionic acid, Y Y c 1 Solutions according to the invention should be operated at a pl-l. in the range from 6.5 to 12, most suitably from pH 7.0 to'pH 8.0. Cathode-current density may be from to 80 'ampe're'spejr square foot. Temperature may. be from normal room temperature to 160 F., most suitably from 120 F 0 1407 F.

Concentrations per liter of the'jvarious a'gentslpresen't in which the solutionsin additionto water may be as follows: Nickel compound supplying nickel ions, molecular equivalent of f rom .75 'to "350 grams .of' nickel sulfate hexa- The compounds of this class which we prefer to use are 9 where n is an integer from 2 to 3, m is an integer from 0 to 2 and k is an integer from 1 to 4.

In the practice of the invention,=nickel is-supplied by maintaining in the plating solution a suitable source of nickel which desirably may be nickel sulfate, nickel chloride or a mixture thereof. While good deposits can be produced from an aqueous solution containing only the nickel compound and the complexing agent (e. g. at two parts nickel sulfate hexahydrate and one part ethylene diamine tetra acetic acid to twenty parts water, all by weight), it is desirable to have present in the solution other agents which serve useful purposes. In order to maintain conveniently an optimum pH range a buffering agent should be included. This may be for example sodium citrate. We have found also that an organic amine such as an alkanolamine having from 3 to 12 carbon atoms in the molecule (e. g. triethanolamine) has a definite stabilizing influence on the nickel complex, maintaining solubility under conditions which would otherwise result in precipitation. The chloride radical increases anode corrosion while the nitrate radical decreases hydrogen evolution and permits higher current densities. Ammonium salts, e. g. NH4C1 or (NI-192804, although not indispensable, somewhat improve lustre, ductility and cathode efiiciency. They may be present in proportion from 5 to .grams per liter.

Representative specific polyalkanoic acid derivatives of polyalkyleneamines suitable for realization of the invention are as follows:

( l) Ethylene diamine tetra acetic acid.

(2) Diethylene triamine penta acetic acid.

(3) Mono sodium salt of ethylene diamine tetra acetic acid.

ydra iwmp exin a e rom 1 1 rams; s abilib a x r i flj fro '2 to 00 am .and n t a e optional, from 5.0 to 40.0 grams. Preferredfsolutionsare as follows:

NiSOaHzO, 75-t0 350, preferably to 210-g./l.,-

Ethylene .dia'mine'tetra acetic acid, 25 to :175,- preferably 25 to 150 g./l. Y

Tri'ethanolamine, 0 to 200 cc., preferably, 251cc. -to-l0 -oc./l.'

-Nickel nitrate-:0 'to 40,preferably 5-.0to 30 g./l'.

C. D. (amperes per sq. ft.), 10 to 150, preferably 20 to 80 Temperature (degrees F.), to 180, preferably The following specific examples of the practice of the invention, incorporating the various ingredients which have been found beneficial will serve as illustrations:

Example I NiSO4.'6HaO 100 -g./l. Na citrate 66 g./l. NaCl or NH4C1 35 g./l. Ethylene diamine tetra acetic acid 20-100 g./l. (e. g., 60). Triethanolamine 35-50 cc. (e. g., 40).

Ni(NO3)2 10-30 g./l. (e. g., 20). pH 6.5-12 (e. g., 7.0). Current density 40 amp./ft. Temp 140 F. NaHSOa 3-8 g./l. (e. g., 5).

Example II NaHSOa g 1 3-8 NiClz g l 85 Na citrate g /l 66 NazSOr g l 75 Ethylene diamine tetra acetic acid g./l 40 Triethanolamine cc 40 Ni(NO3)a g /l 20 pH (with NaOH) 7.5

Current density amp./ft. Temp.

Results of plating tes-ts with these two baths at l F. were very'satisfactory. In all cases the deposits were dull semi-bright with fine grained and dense deposits resembling those deposits which are obtained from" the Watts bath and all deposits were ductile with excellent adhesion.

Furthermore, stability of these solutions-is excellent. 7

These two solutions give good deposits andexhibit excellent stability. The deposits are not, however lustrous as in the case of Example I and II.

Having thus described-the invention, what we new claim is. t t

*1. An aqueous, alkaline nickel plating solutionlcomprising a nickel compound of the class consisting of 'nickel chloride, nickel sulfiate and mixtures thereof molecularly equivalent to to 250 grams per liter of nickel sulfate hexahydrate, a complexing agent in concentrationyfroni 25 to 175 grams per liter, said complexing agent-being .a

polyalkanoic acid derivative of a polyalkylene amine soluble in the solution, and a'polyalk-anol amine stabilizer present in concentration from 25 to 200 grains per liter, the pH of said solution being in the range from 6.5 to 12.

2. An electroplating process comprising passing'current from a nickel anode to a cathode to be coated through an aqueous, alkaline nickel plating solution comprising a nickel compound of the class consisting of'nickel chloride, nickel sulfate and mixtures thereof molecular-1y equivalent to 75 to 250 grams per liter of nickel sulfate 40 'hexahydrate, a complexing'agen-tin concentration from 25 to 175 grams per liter, said complexing agent being a polyalkanoic acid derivative of a polyalkylene amine soluble in the solution, and a polyalkanol amine stabilizer present in concentration from 25 to 200 grams per liter,

the pH of said solution being maintained in the range from 6.5 to 12, the temperature being maintained in the range from 100 F. to 180 'F. and the current density being maintained in the range from 20 to amperes per square 5 foot.

3. An aqueous, alkaline nickel pl-ating solution comprising, in addition to water, from to 210 grams per liter of nickel sulfate hexahydrate, from 25 to 150 grams per liter of ethylene diaminetetra acetic acid, from 25 to 1 00 grams per liter of triethanolamine, the pH of said solution being from 6.8 to 9.0.,

4. An electroplating process comprising passing current from a nickel anode to a cathode to be coated through an aqueous alkaline nickel plating solution comprising, in addition to water, from 85 to 210 grams per liter of nickel sulfate hexahydrate, from 25 to 150 grams per liter of ethylene diamine tetra acetic acid and from 25 to grams per liter of triethanolamine, the pH being maintained in the range from 6.8 to 9.0, the temperature being maintained in the range from F. to F. and the cathode current density being maintained in the range from 20 to 80 amperes per square foot.

5. An aqueous, alkaline nickel plating solution comprising nickel sulfate equiv-alent to 75 to 250 grams per liter of nickel sulfate hexahydrate, a complexing agent in concentration from 25 .to grams per liter, said complexing agent being a polyalkanoic acid derivative of a polyalkylene amine soluble in the solution, a polyalkanol amine stabilizer in concentration from 25 to 200 grams per liter, a buffering agent and from 5 to 30 grams per liter of nickel nitrate, the pH of said solution being in the range from 6.5 to 12.

References Citedin the file of this patent 35 UNITED STATES PATENTS 2,678,910 Brown May 18, 1954 FOREIGN 'PATENTS' 731,102 Germany Feb. 3, 194

OTHER REFERENCES Sequestrene, Alrose Chemical 00., Providence, R. 1., July 1952, page 28. Y

Versenesf Bersworth Chemical Co., Framingham, 45 Mass, February 1952, pages 46-48. 

1. AN AQUEOUS, ALKALINE NICKEL PLATING SOLUTION COMPRISING A NICKEL COMPOUND OF THE CLASS CONSISTING OF NICKEL CHLORIDE, NICKEL SULFATE AND MIXTURES THEREOF MOLECULARLY EQUIVALENT TO 75 TO 250 GRAMS PER LITER OF NICKEL SULFATE HEXAHYDRATE, A COMPLEXING AGENT IN CONCENTRATION FROM 25 TO 175 GRAMS PER LITER, SAID COMPLEXING AGENT BEING A POLYALKANOIC ACID DERIVATIVE OF A POLYALKYLENE AMINE SOLUBLE IN THE SOLUTION, AND A POLYALKANOL AMINE STABILIZER PRESENT IN CONCENTRATION FROM 25 TO 200 GRAMS PER LITER, THE PH OF SAID SOLUTION BEING IN RANGE FROM 6.5 TO
 12. 